Non-stalling gasoline fuel compositions



United States Patent NON-STALLING GASOLINE FUEL COMPOSITIONS Gardner'E.'Gaston, Tarentum, and John P. 'Pellegrini, Jr.,

Blawnox, Pa., 'assignors to Gulf Research 8; Development Company,Pittsburgh, Pa, n corporation of Delaware No Drawing. ApplicationSeptember 12, 1955 Serial No. 533,920

6 Claims. (CI. 44-58) This invention relates to non-stalling gasolinefuel compositions that are adapted to improve the operation of internalcombustion engines under cool, humid atmospheric conditions. Moreparticularly, the invention relates to gasoline fuel compositions thatcontain a small amount, sufficient to reduce the tendencies of thecomhaving a relatively low 50 percent ASTM distillation p'oint, enginestalling is apt to be encountered at idling speeds during the warm-upperiod, especially where engine idling occurs following a period oflight load opera 'tion. Engine stalling under such conditions has beenattributed to the partial or complete blocking of the narrow air passagethat exists between the carburetor throat and the carburetor throttlevalve during engine idling, by ice particles and/ or solid hydrocarbonhydrates that de posit upon and adhere to the metal surfaces of thecarburetor parts. Such icing of carburetor parts occurs as a result ofthe condensation of moisture from the air drawn into the carburetor andas a result of the solidification of such condensed moisture. Theaforesaid condensation and solidification of moisture are caused by therefrigeratin'g "effect of rapidly evaporating gasoline. Accordingly,excessive engine stalling due to carburetor icing occurs as a practicalmatter only in the instance of gasolines containing a large proportionof relatively highly volatile components.

Excessive engine stalling is, of course, a source of annoyance owing tothe resulting increased fuel consumption, battery wear and inconvenienceof frequent restarting. It is therefore important that in inherentengine stalling characteristics of gasoline fuels be reducedsubstantially, where 50 percent ASTM distillation point of such gasolinefuels is sufficiently low to cause a problem in this respect.

We have found that the stalling characteristics of gasoline fuelcompositions having a 50 percent ASTM distillation point below about 220F. and that normally tend to promote engine stalling due to carburetoricing are markedly improved by the incorporation therein of a smallamount of the oil-soluble still bottoms from the distillation of theproducts obtained by subjecting a mono-olefin containing 6 to 8 carbonatoms to the 0x0 synthesis process, to recover primary alcoholscontaining one more carbon atom than the mono-olefin. In one embodimentof the invention the gasoline composition also contains about 0.25 toabout 0.75 percent by volume of the composition of a light lubricatingoil having a viscosity at 100 F. of about 50 to about 500 SayboltUniversal seconds.

The 0x0 bottoms anti-stalling agents disclosed herein containsubstantial proportions of polar, surface-active ice materials. Whilethe invention is not limited to any theory of operation, it might appearthat these polar components tend to orient themeselves upon the metalsurfaces of the throttle valve and other critical carburetor partscontacted by the gasoline composition, thus forming amoisture-displacing, residual coating on said carburetor parts, whichcoating tends to prevent the adherence to said metal surfaces ofaccumulations of ice of magnitudes sutficient to block the narrow airpassages that exist in carburetor throats at engine idling conditions.It isalso considered that the polar components of the 0x0 bottoms mayorient themselves about small individual water 'or ice particles, thustending to prevent the formation of macrocrystals of ice of a sizesufficient to block carburetor -air passages at engine idlingconditions. Although the effectiveness of the herein disclosed additionagents is believed to be attributable at least in part to thepolarcharacteristics thereof, this :general explanation is somewhatnegatived by the fact that many oil-soluble polar agents have little orno effect upon engine stalling due to carburetor icing.

When the herein disclosed Oxo bottoms anti-stalling agents are utilizedin gasoline compositions that contain a small amount of a lightlubricating oil, it might appear that the 0x0 bottoms, by virtue of itsafiinity for the lubricating oil, tends to attract the oil to the samecritical carburetor surfaces referred to above, while simultaneouslyincreasing the spreading and .metal wetting characteristics of the oil,thus promoting the formation "of an adherent oil film on the metalsurfaces of the carburetor parts. The oil film therefore would appear tofunction similarly as the Oxo bottoms, but the superior metal wettingproperties imparted to the oil by the additives are believed to enablethe oil to displace moisture from metal carburetor surfaces that itwould not thoroughly displace alone.

The oil-soluble Oxo bottoms which are suitable for the purposes of thisinvention are believed to comprise complex mixtures containingpredominantly materials from the group of acetals, hemi-acetals, esters,ethers, aldol condensation products, alcohols and acids. Oil-soluble Oxobottoms included by this invention are obtainable as still bottoms fromthe distillation of the products obtained by subjecting a mono-olefincontining 6 to 8 car bon atoms to the Oxo synthesis process, to recoverprimary alcohols containing one more carbon atom than the mono-olefin.Thus, for example, the 0x0 bottoms obtained as still bottoms from thedistillation of C OX0 alcohols from the product obtained by subjectingmixed heptene isomers to the 0x0 synthesis process might contain C16 17esters, c3 acids, (:16 a lCOhQlS, C16 aldol Con densation products, Cacetals, C hemiacetals, and C ethers.

The Oxo synthesis process .is well known in this country, beingpracticed commercially by several manufacturers. Briefly, this processcomprises subjecting a monoolefin, such .as hexene, heptene, or octene,usually in the form of a mixture of isomers such as can be obtained byfractionation of the products obtained by non-selective polymerizationof the C C or mixed C andC monoolefins present in petroleum refinerygases, 'to hydroformylation in order to form a mixture of oxygenatedproducts, principally aldehydes having one more carbon atom per moleculethan the original mono-olefin. The aldehydic 'hydroformylation productsare then subjected to catalytic hydrogenation to form a mixturecontaining predominantly isomeric branched chain primary monohydricalcohols containing one more carbon atom per molecule than the originalmono-olefin. The hydroformylati-on reaction is normally effected byreacting the mono-olefin with equimolar proportions of hydrogen 4purposes of this invention.

and carbon monoxide at a pressure of about 1500 to about 4500 p. s. i.g., and at a temperature of about 260 to about 460 F., in the presenceof a cobalt catalyst, usually in the form of a salt of a suitableorganic acid such as a naphthenic acid or a fatty acid, the latterpreferably containing at least 6 carbon atoms per molecule. Thecatalytic hydrogenation of the aldehydic'hydroformylation product isnormally effected with gaseous hydrogen in the presence of a suitablehydrogenation catalyst, e. g., nickel, nickel oxide, molybdenum sulfideand the like, preferably deposited upon an inert carrier, at a pressureof about 50 to about 5000 p. s. i. g. and at a temperature of about 290to about 400 F.

Distillation of the products of the x0 synthesis reaction will yield amajor proportion of a mixture of isomeric primary monohydric alcoholscontaining one more carbon atom per molecule than the mono-olefincharged to the hydroformylation reaction, and an Oxo bottomsdistillation residue comprising a minor fraction of the over-all Oxosynthesis product, for example, percent. In the case of the stillbottoms products, the use of which is included by this invention, thebottoms products will comprise predominantly materials boiling above theboiling point of the highest boiling isomer of the primary alcoholmixture produced in the 0x0 synthesis reaction. Thus, in the instance ofthe Oxo bottoms obtained from the distillation of C Oxo alcohols, thebottoms product will comprise predominantly material boiling above about331 F. at 760 mm. Hg. In the instance of the Oxo bottoms productobtained from the distillation of C alcohols, the bottoms product willcomprise predominantly material boiling above about 378 F. at 760 mm.Hg. In the instance of the 0x0 bottoms product obtained from thedistillation of C Oxo alcohols, the bottoms product will comprisepredominantly material boiling above about 401 F. at 760 mm. Hg. Oxobottoms obtained from the sources indicated above, the predominantportion of which boils above the respective specified temperatures, aresuitable for the It should be noted that the specific temperatures setforth above are temperatures above which substantially all, but notnecessarily one hundred per cent, of the bottoms product will boil,since it will be appreciated that the presence of small amounts of 0x0alcohols or water in the still bottoms can lower the initial boilingpoint somewhat below the values specified above. A specific example ofan Oxo bottoms product, the use of which is included by the inventionand with which excellent results have been obtained, is the oil-solublestill bottoms obtained by distillation overhead of C Ox-o alcohols fromthe product obtained by hydroformylation of mixed heptene isomers,obtained in turn by fractionation of the product of non-selectivepolymerization of mixed C C olefin fraction, at 3500 p. s. i. g. and 350F., in the presence of a cobalt octanoate catalyst, and by hydrogenationof the resulting aldehydic product with gaseous hydrogen at 1000 p. s.i. g. and 380 F. in the presence of a reduced nickel oxide catalyst. Atypical sample of the still bottoms as indicated above was found to beessentially completely insoluble in water and to have the followingadditional characteristics Inspections:

Acetyl No 166.8 Hydroxylamine No 159.4 Neutralization No 9.9Saponification No 39 Specific gravity: 68/68 F 0.8569

Distillation, F. (corrected to 760 mm. Hg):

Over point 327 End point (extrapolated) 730 2% evap. at F. (corrected to760 mm.

Since the boiling point of the highest boiling isomer present in C Oxoalcohols is approximately 378 F. at 760 mm. Hg, essentially all 99percent) of the bottoms product described above boiled above thistemperature. The low initialv boiling point for the abovedescribed stillbottoms product is attributable to the presence of a small amount ofwater.

The Oxo bottoms anti-stalling agents described herein are useful whenincorporated in gasoline compositions of the type disclosed in an amountsufficient to reduce the engine stalling characteristics thereof. Forexample, a good improvement in the stalling characteristics of gasolinesof the type disclosed will normally be obtained by the addition theretoof the herein disclosed Oxo bottoms products in amounts of at least 0.05percent by volume of the composition. Preferably the 0x0 bottomsantistalling agents disclosed herein will be employed in proportions ofat least about 0.2 percent by volume of the composition. Excellentresults have been obtained by the addition of 0x0 bottoms of the kinddisclosed herein to gasoline compositions in proportions between 0.2percent and 1.0 percent by volume of the composition, and thisconstitutes the preferred concentration range for the purposes of thisinvention. Although in some instances it may be desired to employ the0x0 bottoms anti-stalling agents in amounts of up to about 1.75 percentby volume or more, such higher concentrations are less preferred sincethe degree of improvement in the stalling characteristics of thegasoline, per unit increment of Oxo bottoms, is relatively low. In noinstance should the 0x0 bottoms additive disclosed herein be added tothe gasoline in amounts such as to produce an undue adverse effect onthe volatility, combustibility, anti-knock or gum-formingcharacteristics of the gasoline.

It will be appreciated that the optimum concentration of the disclosedOxo bottoms anti-stalling agents can vary within the disclosed rangeaccording to the particular gasoline employed, since the problem ofengine stalling due to carburetor icing is a function of the 50 percentASTM distillation point of the gasoline. Thus, greater concentrations ofthe additive are normally desirable with decreasing 50 percent ASTMdistillation point. The optimum concentration of the OX0 bottomsanti-stalling agents can also vary somewhat according to the particularmake and model of engine in which the gasoline is used and alsoaccording to the severity of the atmospheric conditions encountered.With regard to the last mentioned factor, the problem of engine stallingdue to carburetor icing resulting from the refrigeration by evaporatinggasoline of moisture condensed from the atmosphere has been observed tobe significant at temperatures between about 30 and 50 F., e. g., 35,40, 45, 50 F., and when the relative humidity is in excess of about 65percent, e. g., 75, 85, 99 percent. The optimum concentration of the OX0bottoms anti-stalling agents will be one that is suflicient to effect asubstantial reduction in the stalling tendencies of the fuel at theatmospheric conditions of tempertaure and humidity which are likely tobe encountered in service.

Practically speaking, the problem of engine stalling due to carburetoricing caused by rapid evaporation of gasoline occurs only in connectionwith gasolines having a 50 percent ASTM distillation point of notgreater than about 235 F. Accordingly, this invention relates only togasolines of this type. While occasional engine stalling may occur as aresult of carburetor icing at severe atmospheric conditions oftemperature and humidity With gasolines having somewhat higher 50percent ASTM distillation points, experience has indicated that theproblem does not assume major importance except with gasolines of thecharacter indicated. The problem of engine stalling due to carburetoricing is especially severe in connection With gasolines having a 50percent ASTM distillation point of less than about 220 F. The inventionis particularly useful in connection with such gasolines. The termgasoline is used herein in its conventional sense to include hydrocarbonmixtures having a 90 percent ASTM distillation point of not more thanabout 392 F. and a percent ASTM distillation point of not less thanabout 140.

As previously indicated, the gasoline compositions of this invention areadditionally benefited with respect to non-stalling characteristics bythe inclusion therein of a small amount of a lubricating oil having aviscosity at 100 F. of between about 50 and about 500 Saybolt Universalseconds; for example, an oil having a viscosity of about 100 S. U.S./l00 F. can be used with advantage. Although highly parafiiniclubricating distillates can be used, lubricating distillates obtainedfrom Coastal or naphthenic type crude petroleum oils are preferredbecause of their superior solvent properties. The lubricating oilsutilized in the gasoline compositions of this invention can have beensolvent-treated, acid-treated or otherwise refined prior toincorporation into the gasoline compositions of this invention. Thelubricating distillates referred to are useful in the gasolinecompositions of this invention in amounts of from about 0.25 to about0.75 percent by volume of the composition, for example 0.5 volumepercent. In such concentrations these lubricating distillates tend toassist the anti-stalling function of the 0x0 bottoms and in additionfunction as upper cylinder and valve top lubricants. Greater amounts ofthe lubricating oil can be used but without appreciable furtherimprovement in the stalling tendencies of the gasoline composition;however, the amount of lubricating oil used should not be so great as toadversely aifect the solubility and combustion characteristics of theultimate gasoline compositions.

The Oxo bottoms anti-stalling agents of this invention can beincorporated into the base gasoline fuel compositions in any suitablemanner. Thus, they can be added as such to gasoline or in the form of adispersion or solution in solvents such as butanol, isopropanol,ethanol, methanol, 2-butoxyethanol, diethylene glycol monobutyl ether,benzene, toluene, heptane, kerosene, gasoline, mineral oil or the like,which solvents may or may not themselves additionally contribute to theanti-stalling characteristics of the ultimate composition. If desired,the disclosed Oxo bottoms anti-stalling agents can be incorporated ingasoline fuel compositions in admixture with other materials designed toimprove one or more properties of the gasoline such as antioxidants,fanti-gumming agents, anti-knock agents, e. g., tetraethyl lead, leadscavenging agents, e. g., ethylene dibromide, ignition controladditives, d'e-icing agents, corrosion inhibitors, dyes and the like.

Gasoline compositions of this invention can be further illustrated bythe following representative specific examples.

EXAMPLE I Gasoline compositions according to this invention and havingreduced engine stalling tendencies were prepared by incorporation inseparate samples of a gasoline having a strong tendency as such topromote engine stalling of, respectively, 0.1, 0.25, and 0.5 volumepercent of the above-described 327 -730 boiling range Oxo bottoms 6obtained as still bottoms from the distillation of a C Oxo alcoholproduct. A typical sample of the base gasoline employed in thesecompositions had the following inspections:

Gravity, API 64.4 Sp. gr., 60/60 F 0.7223 Anti-knock rating, octane No.2

An additional gasoline composition in accordance with this invention andhaving reduced engine stalling characteristics can be obtained byadmixture of 0.25 volume percent of the 0x0 bottoms of Example I withthe base gasoline described in Example I, to which there has beenpreviously added 0.5 percent by volume of an approximately 100 S. U. S./100 F. Texas (Coastal) lubricating distillate, a sample of which has thefollowing inspections:

Gravity, API 24.5 Viscosity, SUV, sec.:

70 F 235 100 F 106 130 F 63.9 210 F 38.3 Viscosity index 16 Pour, F M--60 Carbon residue, Conradson, percent 0.02

The foregoing specific embodiments of the compositions of this inventionare illustrative, and other suitable compositions within the scope ofthis invention and having good engine stalling characteristics can beprepared similarly by the substitution in the foregoing examples ofother gasolines of the type disclosed herein and tending to promotecarburetor icing and by the use of other proportions within the rangedisclosed herein of the 0x0 bottoms products described in the foregoingexamples or other Oxo bottoms products disclosed herein.

As heretofore indicated, the Oxo bottoms anti-stalling agents of thisinvention produce an appreciable improvement in the stallingcharacteristics of gasolines that normally tend to promote enginestalling due to carburetor icing. To illustrate the nature of theimprovement obtained, in the table following there are presentedillustrative results obtained with engine tests using gasoline fuelcompositions prepared in accordance with this invention. In order todemonstrate the unusual effectiveness of the 0x0 bottoms anti-stallingagents of this invention, there are also presented in the table belowthe results obtained with engine tests of a sample of the uninhibitedtest gasoline.

According to the test procedure followed the fuel compositions to betested were fed to a standard, 216 cubic inch displacement, 6-cylinderoverhead valve Chevrolet engine, the air supply to the carburetor of theengine being obtained by natural aspiration from a cold room atmosphere.The engine was equipped with a standard Carter downdraft carburetor. Theambient temperature of the cold room was 40 F., and the relativehumidity was to percent.

The first operating cycle of the engine included, after permitting theengine to cool to the ambient tempera- 7 ture of 40 F., starting theengine and running for 40 seconds at 2000 R. P. M. and then for 20seconds at 500 R. P. M. (idle) under no load, or until the enginestalls. Repetition of the foregoing cycle 20 times con- 8 amount of oilsoluble Oxo still bottoms is about 0.05 to about 1.75 percent by volumeof the composition.

4. The composition of claim 1 wherein said small amount of oil-solubleOxo still bottoms is about 0.2 to

stituted one test. about 1.0 percent by volume of the composition.

Table Composition Concentration, Engine Test, Stalls percent PerOperating Base Fuel Additive by Vol- Cycles ume 10 (avg, 8 tests).

Base Gasoline, 206 F. 50% ASTM Distillation Point (Example I Base Fuel).

0. 1 7 (avg., 3 tests).

0. 3.75 (avg, 4 tests). 0. 5 3.3 (avg., 6 tests).

From the results presented in the foregoing table it will be seen thatuninhibited gasolincs having a 50 percent ASTM distillation point in therange disclosed possess poor stalling characteristics. In contrast, anuninhibited gasoline having a 50 percent ASTM distillation point of 240F. produced an average number of stalls approaching zero in 20 operatingcycles. From the foregoing data it is also apparent that gasolineshaving a 50 percent ASTM distillation point within the range disclosedare markedly improved by incorporation therein of the herein disclosedproportions of the OX0 bottoms anti-stalling agents of this invention.

To the gasoline fuel compositions of this invention there can also beadded one or more additional additive agents designed to improve one ormore characteristics of the gasoline fuel. For example, antioxidants,anti-knock agents, ignition control agents, other de-icing agents,antirust agents, dyes, lead scavenging agents, anti-gumming agents andthe like can be added to the compositions of this invention, and theinvention specifically includes gasoline compositions containing suchadditives.

Numerous additional embodiments of the invention will readily suggestthemselves to those skilled in the art. Accordingly, we do not intend tobe limited by the foregoing description, but only by the terms of theclaims appended hereto.

We claim:

1. A gasoline fuel composition comprising a major amount of ahydrocarbon mixture boiling in the gasoline range that has a 50 percentASTM distillation point not greater than about 220 F. and that tends topromote stalling of internal combustion engines, and containing a smallamount, sufficient to reduce the engine stalling characteristics of thegasoline composition, of oil-soluble Oxo still bottoms obtained bysubjecting a mono-olefin containing 6 to 8 carbon atoms to the 0x0synthesis process by hydroformylating the -mono-olefin with hydrogen andcarbon monoxide in the presence of a hydroformylation catalyst to forman aldehydic product having one more carbon atom per molecule than theoriginal monoolefin and then hydrogenating the aldehydic product in thepresence of hydrogen and a hydrogenating catalyst to form Oxo alcoholscontaining one more carbon atom per molecule than the originalmono-olefin, and distilling overhead from the reaction products at leastthe major portion of the Oxo alcohols containing one more carbon atomthan the mono-olefin, leaving behind a still bottoms product.

2. The composition of claim 1 wherein the hydrocarbon mixture containsadditionally about 0.25 to about 0.75 percent by volume of thecomposition of a light lubricating oil having a viscosity at 100 F. ofabout 50 to about 500 Saybolt Universal seconds.

3. The composition of claim 1 wherein said small 5. A gasoline fuelcomposition comprising a major amount of a hydrocarbon mixture boilingin the gasoline range that has a percent ASTM distillation point notgreater than about 220 F. and that tends to promote stalling of internalcombustion engines, and containing a small amount, suflicient to reducethe engine stalling characteristics of the gasoline composition, ofoil-soluble Oxo still bottoms obtained by subjecting a mono-olefincontaining 7 carbon atoms to the OX0 synthesis process byhydroformylating the mono-olefin with hydrogen and carbon monoxide inthe presence of a hydroformylation catalyst to form an aldehydic producthaving 8 carbon atoms per molecule and then hydrogenating the adehydicproduct in the presence of hydrogen and a hydrogenation catalyst to formOxo alcohols containing 8 carbon atoms per molecule, and distillingoverhead from the reaction products at least the major portion of the0x0 alcohols containing 8 carbon atoms, leaving behind a still bottomsproduct, the predominant portion of said Oxo still hottoms boiling aboveabout 378 F. at 760 mm. Hg.

6. A gasoline fuel composition comprising a major amount of ahydrocarbon mixture boiling in the gasoline range that has a 50 percentASTM distillation point not greater than about 220 F. and that tends topromote stalling of internal combustion engines, and containing a smallamount, sufiicient to reduce the engine stalling characteristics of thegasoline composition, of oilsoluble OX0 still bottoms obtained bysubjecting a monoolefin containing 7 carbon atoms to the OX0 synthesisprocess by hydroformylating the mono-olefin with hydrogen and carbonmonoxide in the presence of a hydroformylation catalyst to form analdehydic product having 8 carbon atoms per molecule and thenhydrogenating the aldehydic product in the presence of hydrogen and ahydrogenation catalyst to form Oxo alcohols containing 8 carbon atomsper molecule, and distilling overhead from the reaction products atleast the major portion of the Oxo alcohols containing 8 carbon atoms,leaving be bind a still bottoms product, said Oxo still bottoms havingthe following approximate inspections:

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2 843463 July 15, 1958 Gardner E0 Gaston et all It is hereby certified thaterror appears in the-printed. specification of the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 5 line 17 for "less than about 140" read more than about Signedand sealed this 16th day of September 19580 KARL Ho AXLINE ROBERT C.WATSON Commissioner of Patents Attcsting Officer

1. A GASOLINE FUEL COMPOSITION COMPRISING A MAJOR AMOUNT OF AHYDROCARBON MIXTURE BOILING IN THE GASOLINE RANGE THAT HAS A 50 PERCENTASTM DISTILLATION POINT NOT GREATER THAN ABOUT 220*F. AND THAT TENDS TOPROMOTE STALLING OF INTERNAL COMBUSTION ENGINES, AND CONTAINING A SMALLAMOUNT, SUFFICIENT TO REDUCE THE ENGINE STALLING CHARACTERISTICS OF THEGASOLINE COMPOSITION, OF OIL-SOLUBLE OXO STILL BOTTOMS OBTAINED BYSUBJECTING A MONO-OLEFIN CONTAINING 6 TO 8 CARBON ATOMS TO THE OXOSYNTHESIS PROCESS BY HYDROFORMYLATING THE MONO-OLEFIN WITH HYDROGEN ANDCARBON MONOXIDE IN THE PRESENCE OF A HYDROFORMYLATION CATALYST TO FORMAN ALDEHYDIC PRODUCT HAVINE ONE MORE CARBON ATOM PER MOLECULE THAN THEORIGINAL MONOOLEFIN AND THEN HYDROGENATING THE ALDEHYDIC PRODUCT IN THEPRESENCE OF HYDROGEN AND A HYDROGENATING CATALYST TO FORM OXO ALCOHOLSCONTAINING ONE MORE CARBON ATOM PER MOLECULE THAN THE ORIGINALMONO-OLEFIN, AND DISTILLING OVERHEAD FROM THE REACTION PRODUCTS AT LEASTTHE MAJOR PORTION OF THE OXO ALCOHOLS CONTAINING ONE MORE CARBON ATOMTHAN THE MONO-OLEFIN, LEAVING BEHIND A STILL BOTTOMS PRODUCT.
 2. THECOMPOSITION OF CLAIM 1 WHEREIN THE HYDROCARBON MIXTURE CONTAINSADDITIONALLY ABOUT 0.25 TO ABOUT 0.75 PERCENT BY VOLUME OF THECOMPOSITION OF A LIGHT LUBRICATING OIL HAVING A VISCOSITY AT 100*F. OFABOUT 50 TO ABOUT 500 SAYBOLT UNIVERSAL SECONDS.